The sealed Legends are an obvious reference to Dio. They're pretty much a mix between the devil silhouette that appears in the original Holy Diver music video, and the "Master of the moon" album cover.

Master of the moon cover:

I couldn't find a picture of the silhouette, but here's the Holy Diver album cover. It's not as obvious, but it's pretty much the same anyways.

Also.. do you think the Bleeding Deaths(the creatures summoned by Dovicolus at the Pleasure Dome)might be a grudge thing against Iron Maiden for not wanting to be in the game? You know... this whole being sealed inside an actual iron maiden and all.. probably not, but it IS fun to think about